The invention relates to a new use of protein C in preparing a pharmaceutical preparation. The invention also relates to new pharmaceutical preparations containing the activation peptide of protein C, optionally admixed with protein C or activated protein C.
Protein C is a vitamin K-dependent glycoprotein that is synthesized in the liver and circulates in plasma as an inactive zymogen at a concentration of about 4 .mu.g/ml. It is converted into an active serine protease, activated protein C, by the thrombin-thrombomodulin complex on the surface of the vessel wall (endothelium). It is known that activated protein C has profibrinolytic properties. It also has an anticoagulant effect, since it proteolytically degrades both Factor Va, the cofactor for Factor Xa-induced prothrombim activation (thrombin formation), and Factor VIIIa, the cofactor for Factor IXa-induced Factor X activation.
The protein C zymogen circulates in the plasma primarily in a two-chain form containing a heavy and light chain that are disulfide bonded to one another. Activation of protein C involves the cleavage of the NH.sub.2 --terminal 12 amino acids of the heavy chain of the molecule. Cleavage occurs between Arg.sup.12 --Lys.sup.13 of the heavy chain to release the activation peptide of protein C, which has the following amino acid sequence (designated as SEQ. ID. NO. 1):
NH.sub.2 -Asp-Thr-Glu-Asp-Gln-Glu-Asp-Gln-Val-Asp-Pro-Arg-COOH
Patients that are deficient in or lacking protein C show pronounced thrombotic or clotting tendencies. Babies born with a complete deficiency of protein C exhibit massive disseminated intravascular coagulation (DIC) and a necrotic syndrome that can lead to death in the first few weeks of life, if untreated.
Activated protein C has anticoagulant properties and has been shown to protect animals against the coagulopathic and lethal effects of endotoxin shock. Taylor, et al., J. Clin. Invst. 79:918-925 (1987).
Moreover, in U.S. patent application Ser. No. 540,357 a pharmaceutical preparation is described which contains protein C and may be employed for the treatment or the prevention of thromboses and thromboembolic complications.
More specifically, it is activated protein C that can inhibit arterial thrombolytic occlusion or thromboembolism. (See, e.g., U.S. Pat. No. 5,084,274 of Griffin et al.). The non-activated zymogen does not have this effect. For example in Gruber, et al., Blood 73:639-642 (1989), the in vivo antithrombotic properties of activated human protein C were studied in a baboon model of thrombus formation on prosthetic vascular grafts. Thrombotic occlusion was prevented in animals infused with activated protein C, but was not in those (control) animals administered protein C or saline.
Recently, a Ca.sup.2+ dependent monoclonal antibody, HPC-4, that specifically recognizes an epitope in the activation region of protein C has been described. See, e.g., U.S. Pat. No. 5,202,253 of Esmon et al. This antibody, which recognizes an epitope spanning residues 6-17 at the NH.sub.2 terminus of the heavy chain of protein C, i.e., the activation region, binds to protein C, but not to activated protein C. The amino acid sequence (SEQ. ID. NO. 2) of the peptide specifically recognized by the HPC-4 antibody is:
NH.sub.2 -Glu-Asp-Gln-Val-Asp-pro-Arg-Leu-Ile-Glu-Gly-Lys-COOH
Administration of HPC-4 to animals in vivo has been shown to block the activation of protein C and may be useful in stemming blood loss during surgical or other procedures. See, e.g., WO 94/02172.
It has now been found that protein C, specifically the activation peptide of protein C, has anti-nociceptive and anti-inflammatory activities and may be useful in compositions and methods for alleviating or treating the pain associated with the inflammatory process.